1. Field of the Invention
The present invention relates to movable body drive methods, movable body apparatus, exposure methods, exposure apparatus, and device manufacturing methods, and more particularly to a movable body drive method in which a movable body is driven along a predetermined plane, a movable body apparatus including the movable body, an exposure method which uses the movable body drive method, an exposure apparatus which is equipped with the movable body apparatus, and a device manufacturing method which uses the exposure method or the exposure apparatus.
2. Description of the Background Art
Conventionally, in a lithography process for manufacturing microdevices (such as electron devices) such as semiconductor devices, liquid crystal display devices and the like, exposure apparatuses such as a projection exposure apparatus by a step-and-repeat method (a so-called stepper) and a projection exposure apparatus by a step-and-scan method (a so-called scanning stepper (which is also called a scanner) are mainly used.
In this kind of exposure apparatus, in order to transfer a pattern of a reticle (or a mask) on a plurality of shot areas on a wafer, a wafer stage holding the wafer is driven, for example, by linear motors and the like. In this case, position measurement of the wafer stage has been generally performed, using a laser interferometer which is stable and has high resolution.
However, requirements for a stage position control with higher precision are increasing due to finer patterns that accompany higher integration of semiconductor devices, and now, measurement errors resulting from air fluctuation generated by temperature variation of the atmosphere on the beam path of the laser interferometer or by temperature gradient has come to occupy a large percentage in the overlay budget.
As a position measuring device of the stage instead of the laser interferometer, an encoder (for example, U.S. Pat. No. 7,238,931) is promising. However, while the encoder is superior to the laser interferometer in the viewpoint of measurement reproducibility because of using a scale, it is inferior to the laser interferometer for the mechanical instability (drift of the grating pitch, fixed location drift, thermal expansion and the like) of the scale in the viewpoint of linearity.
In view of the drawbacks of the laser interferometer and the encoder described above, various proposals are being made (refer to, for example, U.S. Patent Application Publication No. 2007/0288121, or U.S. Patent Application Publication No. 2009/0027640 and the like) of methods used to measure the position of a stage using both a laser interferometer and an encoder (a position detection sensor which uses a diffraction grating). However, the methods and the like disclosed in these U.S. Patent Application Publication and the like are still not sufficient enough when ensuring a highly accurate and stable position control performance of the stage which is required in the current exposure apparatus.